Omega-3 fatty acids are fatty acids found in certain fish tissues, and also in some vegetable foods such as green leaves.

Omega-3 fatty acids are classed as essential fatty acids. These fatty acids were originally designated as "Vitamin F", until it was realized that they must be classified with the fats. The essential omega-3 fatty acid that the body cannot manufacture is EPA, eicosapentanoic acid[?].

The term "omega-3" signifies that the first double bond in the carbon backbone of the fatty acid, counting from the end opposite the acid group, occurs in the third carbon-carbon bond.

A number of remarkable benefits have been attributed to omega-3 fatty acids in recent years. However, these are so far provisional results, and cannot yet be regarded as fact until they have been confirmed by further studies.

There are preliminary reports that supplementing the diet with large doses of omega-3 oils may act as a mood stabilizer, opening the possibility of their use as a treatment for bipolar disorder. However, the reports relating to this state that care must be taken to avoid overdose, and more research is needed.

Lower doses have also been reported as having possible beneficial cardiovascular effects,

there are also initial reports that omega-3 fatty acids may lower the risk of dementia in old age.